Division by zero in TFLite's implementation of `OneHot`

### Impact The implementation of the `OneHot` TFLite operator is [vulnerable to a division by zero error](https://github.com/tensorflow/tensorflow/blob/f61c57bd425878be108ec787f4d96390579fb83e/tensorflow/lite/kernels/one_hot.cc#L68-L72): ```cc int prefix_dim_size = 1; for (int i = 0; i < op_context.axis; ++i) { prefix_dim_size *= op_context.indices->dims->data[i]; } const int suffix_dim_size = NumElements(op_context.indices) / prefix_dim_size; ``` An attacker can craft a model such that at least one of the dimensions of `indices` would be 0. In turn, the `prefix_dim_size` value would become 0. ### Patches We have patched the issue in GitHub commit [3ebedd7e345453d68e279cfc3e4072648e5e12e5](https://github.com/tensorflow/tensorflow/commit/3ebedd7e345453d68e279cfc3e4072648e5e12e5). The fix will be included in TensorFlow 2.5.0. We will also cherrypick this commit on TensorFlow 2.4.2, TensorFlow 2.3.3, TensorFlow 2.2.3 and TensorFlow 2.1.4, as these are also affected and still in supported range. ### For more information Please consult [our security guide](https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md) for more information regarding the security model and how to contact us with issues and questions. ### Attribution This vulnerability has been reported by members of the Aivul Team from Qihoo 360.

CVSS 3.1

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L

Severity from

GitHub (reviewed advisory)

Weakness

CWE-369

Also known as

BIT-tensorflow-2021-29600, CVE-2021-29600, PYSEC-2021-237, PYSEC-2021-528, PYSEC-2021-726

• github.com/tensorflow/tensorflow/security/advisories/GHSA-j8qh-3xrq-c825
• nvd.nist.gov/vuln/detail/CVE-2021-29600
• github.com/tensorflow/tensorflow/commit/3ebedd7e345453d68e279cfc3e4072648e5e12e5
• github.com/pypa/advisory-database/tree/main/vulns/tensorflow-cpu/PYSEC-2021-528.yaml
• github.com/pypa/advisory-database/tree/main/vulns/tensorflow-gpu/PYSEC-2021-726.yaml
• github.com/pypa/advisory-database/tree/main/vulns/tensorflow/PYSEC-2021-237.yaml
• github.com/tensorflow/tensorflow
• github.com/tensorflow/tensorflow/blob/f61c57bd425878be108ec787f4d96390579fb83e/tensorflow/lite/kernels/one_hot.cc#L68-L72